A scan unit according to the present invention is a scan unit including: a reflecting portion for reflecting laser light; and an enclosure portion having a movable object enclosed within a hollow, characterized in that the movable object moves in accordance with an angular velocity of the scan unit, thereby changing a reflecting state of the reflecting portion with respect to the laser light. In one embodiment, the movable object moves in accordance with the angular velocity of the scan unit to cover at least a part of the reflecting portion. In one embodiment, the movable object moves in accordance with the angular velocity of the scan unit to deform the reflecting portion.